Creda T622CW not blowing hot air- but thermostats are OK?

I have a Creda T622CW which has just developed the "no heat" problem again. Last time it was the thermostats that were the problem. This time however I have checked the thermostats visually (the foil is flat- not concave) and have checked them for continuity- they are passing current when disconnected. I have checked the door thermostat too and there's no problem here either. While checking things out, I accidentally snapped a heater coil (lesson to all!!)and so the heater unit has also been replaced. Any comments on this diagnosis/further suggestions/tips on testing the timer unit?